基于虚拟延迟矢量的核心无状态分组调度框架DVRS

现有提供确定性性能保证的核心无状态分组调度策略中,可扩展性的获得通常以中间节点的速率损失为代价,从而导致数据传输突发性的增强,降低了网络资源的利用率。为了减少速率损失,提出一个核心无状态调度框架DVRS(de lay vector reference system),通过运用虚拟延迟矢量技术,在保证端到端延迟上限与V irtua lC lock算法相同的同时,将核心无状态算法的基本速率保证能力从现在的首尾点精确保证提高到逐点精确保证;并利用局部平均法满足用户对处理开销与带宽保证精度的不同需求;另外,由于核心节点操作的相似性,DVRS类算法具有较好的配置渐进性。     

保证速率的核心无状态分组调度算法

提出一种新的核心无状态分组调度算法VCSVC(G)(vector core-stateless virtual clock).该算法在边界节点为分组计算理想模型下各节点对应的虚拟延迟,组成虚拟延迟矢量带在分组头中,是核心节点排序的依据,其长度上限G利用局部平均法实现.证明了VCSVC(G)与VC(virtual clock)具有相同延迟保证能力,计算了实际算法与理想模型速率保证精度的误差上限,并与两种核心无状态代表算法进行了比较分析.结果表明,通过调节参数G,算法可达到开销与速率保证精度的理想折衷,适用于广泛的用户需求.     

延迟容忍网络中基于不同转发行为路由策略研究

在延迟容忍网络(DTN)中,大多数已有的路由算法在整个数据传输过程中采用单一的数据转发行为。本文提出了一种基于人类移动模式设计不同数据转发行为的路由策略。该策略将个体移动划分为两种状态：一种是Normal状态,另外一种为Small状态,在Normal状态时,采用三因素标准来严格选取中继节点,在Small状态时,采用小范围洪泛来降低端到端延迟。仿真结果表明该策略与传统策略相比可有效提高路由效率。     

轮循调度的报文平滑改进算法

传统的轮循算法只是简单的对所有队列进行轮循调度,一次调度发送一个分组,使得不同队列在某种程度上"平等"地使用带宽资源。然而由于分组长度不固定,使得长分组队列可能比短分组队列得到更多的服务,获得更高的带宽,因而其公平性受到很大限制。文章提出一种基于平滑的轮循调度算法,该算法提出两个数据结构体,权值矩阵和权值延伸序列。这两个结构体可以减轻传统算法中存在的报文突发性和公平性所带来的问题,并且具有较小的排序复杂性。最后用ns2进行仿真,结果表明该算法能够提供较好的端到端延迟,从而更好地保证了网络服务质量。     

一种实时无线传感器网络路由协议

针对传感器网络的特点,提出了一种具有实时性的路由协议.该路由协议可以保证端到端的数据传输具有确定的最大时延.该协议采用基于地理位置的数据转发,相邻传感器节点之间定时交换信息,使用无状态单跳延迟保证转发策略,实现了端到端数据传输的实时性保证.当网络某处发生拥塞时,采用后退重新路由策略,实现了对网络拥塞的自适应性.仿真结果显示该实时协议是可行的和有效的,能满足传感器网络实时性应用的需要.     

延迟容忍网络中一种基于拥塞程度的端到端确认机制

端到端传输的可靠性是传输层的重要问题之一,但是由于网络连接的间歇性,延迟可容忍网络(DTN)往往缺乏稳定的端到端路径,这使得传统的端到端可靠性方法无法直接应用在这类网络之中。分析DTN中端到端可靠性机制的基本原理以及存在的主要问题,提出一种新的基于拥塞程度自适应的端到端确认机制,即APR(Active-Passive Receipt),采用主动反馈与被动反馈相结合的方式,根据网络的拥塞状态自适应地调整确认消息的传输方式,限制网络的总体开销,同时保证较合理的传播延时,以求达到较好的综合性能。模拟结果表明:该方法有效地平衡网络开销和延迟性能,并获得较高的消息到达率。     

IMS中基于时延的E2E QOS控制机制

分析了IMS现有的基于策略的QOS(服务质量)机制,提出了一种新的基于策略的E2E(端到端)QOS机制.新的机制主要通过SIP协议的扩展、PDF(策略判决功能)功能的改进实现IMS中的各个层次间的相互协作.仿真结果表明,新机制能够有效地改善IMS中的会话建立时延.     

基于比例区分服务的端到端传输控制

随着网络技术的不断发展,许多新的网络应用需要端到端的服务质量保证。为了解决端到端的服务质量保证和系统公平性等问题,该文提出了一种基于比例区分服务的网络比例公平调度策略——nPFS策略。该调度策略综合考虑了网络效率、用户服务质量要求和系统公平性等多个性能目标,使用比例公平性原则,有效地实现了多性能目标的端到端传输控制,同时保证系统的公平性。实验结果表明:该文提出的网络比例公平调度策略,可以有效保证多服务类间的比例公平,特别是端到端的服务质量比例公平性。     

基于神经网络的场景调度策略

虚拟场景的实时显示是虚拟现实技术的重要研究课题,优化场景的调度策略是解决实时显示的主要方法之一.根据虚拟装配的特点,建立视点状态变化的马尔可夫模型,并且使用径向基函数神经网络挖掘装配过程中视点变化的规律,提出基于神经网络的场景调度策略,利用该策略预测并提前调入装配过程中将要出现的场景.该策略可以使调度更加智能化,提高场景调度的效率,达到实时显示场景的目的.同时该调度策略也可以应用于虚拟现实的其他领域中,如虚拟场景漫游等.     

光突发交换网络的数据突发延滞调度策略分析

目的改善光突发交换(OBS)网络的QoS性能。方法提出了一种新的光迟延线(FDL)缓冲调度方法,即突发延滞调度策略。结果利用FDL将竞争中的低优先级DB做适当延时,通过BCP的二次信令调整OBS网络中该数据突发(DB)的波长信道预约,以解决突发的竞争问题;通过理论分析和系统仿真方法研究了OBS网络业务流量对DB丢失率和端到端时延的影响。结论该策略能有效地解决OBS网络中DB的竞争现象,为高优先级DB提供了端到端的QoS保证。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to